The first step is to roast your corn. If you are using frozen or canned corn, add the corn kernels to a frying pan with a drizzle of olive oil and saute over medium-high heat until the kernels are golden brown. If you are using corn on the cob, you'll want to roast it over direct heat. If you are using your gas range stove, place the corn over the open flame and turn it frequently until golden brown. If you are using a grill, place it on the grill over high heat and turn frequently until golden brown.
If you are using corn from corn on the cob, place a smaller bowl upside down into a large bowl. Place your corn on top of that small bowl, and using a sharp knife, slice the corn off the cob. The kernels will gather nicely into the larger mixing bowl and you don't have this huge mess. Here's a tutorial.
Once your corn is prepped, slice your onions, tomatoes, and cilantro. In a medium-sized bowl mix together your remaining ingredients, the roasted corn, onions, tomatoes, cilantro, fresh lime juice, cojita cheese, chili powder, garlic powder, and salt.
Serve with tortilla chips, on top of a taco salad, or whatever your favorite way is to eat this corn salsa.